Executive Summary

CVE-2026-56211 is a remote code execution vulnerability in libaom, the reference AV1 codec implementation. It arises from insufficient bounds validation in the AV1 encoder's SVC (Scalable Video Coding) layer ID control, which allows an attacker to supply crafted video frame pixels that overlap with internal encoder layer context structures.

Specifically, the encoder control path for setting the active SVC layer ID lacks proper bounds checking, enabling an attacker to select an out-of-range spatial or temporal layer. This causes the function to operate on a non-existent layer context entry, which overlaps with attacker-controlled image data. The attacker can overwrite security-sensitive fields, such as the cyclic refresh map pointer, leading to arbitrary command execution.

Exploitation requires the target service to use libaom with SVC encoding enabled and accept attacker-supplied video frames.

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Impact Analysis

This vulnerability can lead to a full compromise of confidentiality, integrity, and availability (CIA) in affected systems. An attacker can remotely execute arbitrary code by exploiting the vulnerability in fork-based video processing services that use libaom with SVC encoding enabled and accept attacker-supplied video frames.

Successful exploitation allows the attacker to hijack control flow, potentially leading to unauthorized access, data manipulation, service disruption, or further system compromise.

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Detection Guidance

Detection of this vulnerability involves identifying if your system or service uses libaom with SVC encoding enabled and accepts attacker-supplied video frames.

You can check the libaom version installed to see if it is vulnerable (versions before v3.14.0 are affected).

For example, to check the libaom version on a Linux system, you might use commands like:

• pkg-config --modversion libaom
• dpkg -l | grep libaom

Additionally, monitoring logs for crashes or unusual behavior in video processing services that use libaom with SVC encoding enabled may indicate exploitation attempts.

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Mitigation Strategies

The primary mitigation step is to upgrade libaom to version 3.14.0 or later, where the vulnerability has been fixed by adding proper bounds checks for the SVC layer context array.

If upgrading immediately is not possible, consider disabling SVC encoding in libaom or restricting the acceptance of untrusted or attacker-supplied video frames in your services.

Also, monitor your systems for suspicious activity and crashes related to video encoding processes as a temporary measure.

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Compliance Impact

This vulnerability enables full Confidentiality, Integrity, and Availability (CIA) compromise in fork-based video processing services that use libaom with SVC encoding enabled and accept attacker-supplied frames.

Such a compromise could lead to unauthorized access, data manipulation, or service disruption, which may impact compliance with standards and regulations like GDPR and HIPAA that require protection of sensitive data and system integrity.

However, the provided information does not explicitly mention specific compliance impacts or regulatory considerations.

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